diff --git a/lib/SP/Config/ConfigDataInterface.php b/lib/SP/Config/ConfigDataInterface.php
index 5286d3ec..359e93fb 100644
--- a/lib/SP/Config/ConfigDataInterface.php
+++ b/lib/SP/Config/ConfigDataInterface.php
@@ -350,9 +350,9 @@ interface ConfigDataInterface
     public function setCheckUpdates(?bool $checkUpdates): ConfigDataInterface;
 
     /**
-     * @return string
+     * @return string|null
      */
-    public function getConfigHash();
+    public function getConfigHash(): ?string;
 
     /**
      * Generates a hash from current config options
@@ -891,9 +891,9 @@ interface ConfigDataInterface
     public function jsonSerialize();
 
     /**
-     * @return string
+     * @return string|null
      */
-    public function getConfigSaver();
+    public function getConfigSaver(): ?string;
 
     /**
      * @param string|null $configSaver
diff --git a/tests/SP/DatabaseUtil.php b/tests/SP/DatabaseUtil.php
index 527fbf48..b92003fc 100644
--- a/tests/SP/DatabaseUtil.php
+++ b/tests/SP/DatabaseUtil.php
@@ -86,7 +86,7 @@ class DatabaseUtil
     {
         try {
             self::getConnection()
-                ->exec(sprintf('DROP USER \'%s\'@\'%s\'', $user, $host));
+                ->exec(sprintf('DROP USER IF EXISTS \'%s\'@\'%s\'', $user, $host));
         } catch (Exception $e) {
             processException($e);
         }